Permanent magnet material



Patented May 2, 1944 PERMANENT MAGNET MATERIAL Oscar J. Finch, New York,N. Y., and John H.

White, Cranford, N. J., assignors to Bell Telephone Laboratories,Incorporated, New York, N. Y.,a corporation of New York No Drawing.Application September 17, 1941,

Serial No. 411,156

Q 2 Claims. (01. 75-124) This invention relates to permanent magnets andcompositions of material suitable for making permanent magnets.

An object of the invention is to produce compositions of good permanentmagnet properties which are more workable than previously knowncompositions.

Numerous materials for making permanent magnets have hitherto beenproposed and most, if not all, of them have a poor degree ofworkability.

In accordance with the present invention, compositions for makingpermanent magnets contain nickel between 10 and 30 per cent, aluminumbetween 5 and per cent, vanadium between 2 and 10 per cent, cobaltbetween 5 and per cent, copper any amount from 0 up to 10 per cent andthe balance iron. Generally the iron content is around 40 to 70 percent. Compositions similar to the foregoing but including any amount ofcopper not over 10 per cent are disclosed in our application whichdiscloses and claims subject-matter divided from the application uponwhich this patent issues, said application being Serial No. 506,092,filed October 13, 1943, in pursuance to a final requirement fordivision. In order that this may be accomplished, less than maximumamounts of some of the other recited elements are included, althoughthere is no rigid limitation in this respect.

Typical compositions are indicated in the following table:

. Fe Ni Al Co Cu V Per cent Per cent Per cent Per cent Per cent Per cent(a) 60. 4 23. 8 9. 5 11. 5 0 4. 8 (b) 41 28.6 9.5 11.4 4.8 4.8 (c) 50. 4l9. 0 9. 5 ll. 5 4. 8 4.8

When the heat treatment was varied by cooling the material from 1200 C.in air and then aging the coercive force was 472 and the remanence6,556. Before aging the material had a quite substantial coercive forceand remanence but in each case less than after aging- When the samematerial was hot worked and thereafter similarly cooled in Silocel, andthereafter similarly aged, it had a coercive force of 424 and aremanence of 6,047 after cooling but before aging and a coercive force530 and a remanence of 6,265 after aging.

Composition (b) was more readily worked than composition (a) but had asomewhat smaller magnetic energy product. Thus, after casting, heatingto 1200 C. and cooling in air, and then aging for five hours at 650 C.,it had a coercive force of 655 and a remanence of 3,756.

Composition (0) when cast, similarly cooled in Silocel," and similarlyaged had a coercive force of 583 and a remanence of 5,412. These valueswere almost as high before cooling in Silocel as before aging. In fact,the measured remanence was somewhat larger.

When the material (0) was cast and hot worked and then heated to 1200 C.and cooled in Silocel" the coercive force was 490 and the remanence6,698. After aging the coercive force was 480 and the remanence was6,476. With air cooling the remanence was higher but the coercive forcewas considerably lower in each case.

In the foregoing description the process of cooling in Silocel refers tocompletely covering a test sample of material in a substantial body ofSilocel which is a very poor conductor of heat.

Bodies of such materials of any and all shapes commonly employed forpermanent magnets may be magnetized by the usual processes; they areworkable by hot rolling and swaging.

What is claimed is:

1. A workable alloyed composition adapted to be magnetized to serve as apermanent magnet comprising nickel between 10 and 30 per cent. aluminumbetween 5 and 12 per cent, vanadium between 2 and 10 per cent, cobaltbetween 5 and 15 per cent andthe balance iron.

2. An alloyed composition adapted to serve as a magnetic materialcomprising iron 50.4 per cent, nickel 23.8 per cent, aluminum 9.5 percent, cobalt 11.5 per cent and vanadium 4.8 per cent.

' OSCAR. J. FINCH.

JOHN H. WHITE.

